1. Field of the Invention
The present invention relates to multimedia conferencing in general and, more particularly, to adaptive audio delay control for multimedia conferencing.
2. Description of the Related Art
Multimedia conferencing allows two or more participants remote from each other to engage in a conference call in which each of the parties participating in the multimedia conference transmits and receives audio and video data.
To transmit the necessary large amounts of video data over low bandwidth communication lines, video data compression and decompression is often employed. Typically, these compression functions are performed by a coder/decoder (CODEC), which delays the video image by several hundred milliseconds. In general, talking head videos are best understood when the audio and video signals are synchronized to provide actual lip sync or at least substantially synchronized to provide virtual lip sync. Accordingly, most audio/video systems typically insert a predetermined amount of audio signal delay in order to keep the audio signal synchronized with the video signal.
However, the insertion of audio signal delay can often be detrimental to the natural flow of the conversation and to the perceived audio conference quality, resulting in unnatural conference quality. For example, when a first speaker is carrying on a monologue, if a second speaker tries to interrupt at a particular point and the second speaker's audio is delayed, the second speaker will not interrupt the first speaker at the desired time. Such a situation tends to cause confusion, particularly if a plurality of speakers are actively participating in the conference. In addition, added audio signal delay tends to slow down conference dynamics, further resulting in unnatural conference quality.
Accordingly, there is a need to overcome the above-noted problems associated with the prior art.